Surgical Stapling Device

ABSTRACT

A surgical stapling device for sequentially applying a plurality of fasteners to body tissue and simultaneously incising tissue is provided. The surgical stapling device is adapted to receive disposable loading units having staples in linear rows whose length can be between about 30 mm and 60 mm. The disposable loading unit includes a proximal body portion, a mounting assembly and a tool assembly. The mounting assembly is secured to the proximal end of the tool assembly and pivotally mounted about a pivot axis to the distal end of the proximal body portion. A support member or blow-out plate assembly is positioned on opposite sides of the pivot avis and extends between the proximal body portion and the mounting assembly.

This application claims priority to U.S. Provisional application Ser.Nos. 60/327,527 filed Oct. 5, 2001, 60/363,487 Bled Mar. 11, 2002 and60/363,502 filed Mar. 11, 2002. These applications are incorporatedherein by reference in their entireties.

BACKGROUND

1. Technical Field

This application relates to a surgical stapling device for applyingstaples to tissue. More particularly, this application relates to asurgical stapling device having an articulatable tool member forapplying linear rows of staples to tissue and concurrently incising thetissue between the linear rows of staples.

2. Background a Related Art

Surgical devices for grasping or clamping tissue between opposed jawstructure of a tool assembly and thereafter fastening the clamped tissueare well known in the art. These devices may include a knife forincising the fastened tissue. The fasteners are typically in the form ofsurgical staples but two part fasteners formed of a material suitablefor surgical use are also well known.

Typically, the tool member includes a staple cartridge which houses aplurality of staples arranged in at least two laterally spaced rows andan anvil which includes a plurality of staple forming pockets forreceiving and forming staple legs of the staples as the staples aredriven from the cartridge. Generally, the stapling operation is effectedby cam bars that travel longitudinally through the staple cartridge,with the cam bars acting upon staple pushers to sequentially eject thestaples from the staple cartridge. A knife can travel between the staplerows to longitudinally cut and/or open the stapled tissue between therows of staples.

In laparoscopic and/or endoscopic surgical procedures, the surgicalprocedure is performed through a small incision or through a narrowcannula inserted through a small entrance wound in a patient. Inconventional or open procedures, surgeons directly access an operativesite. Because of reduced patient trauma, shortened patient recoveryperiods and substantial reduction in overall cost, laparoscopicprocedures are preferred over open procedures. In order to address thespecific needs of endoscopic and/or laparoscopic surgical procedures,endoscopic surgical stapling devices have been developed which provide asurgeon with easier access to the operative site. Typically, thesestapling devices include an articulatable tool member which is supportedadjacent to the distal end of the stapling device. The tool member canbe selectively manipulated to allow a surgeon to manipulate a toolassembly in a confined space. Tyco Healthcare Group, LP has manufacturedand marketed articulatable endoscopic stapling instruments such as theMULTIFIRE ENDO GIA *30, MULTIFIRE ENDO GIA 60 and ENDO GIA *Universalfor several years. These instruments have provided significant clinicalbenefits to the field of endoscopic surgery. Nonetheless, improvementsin the area of reducing cost and complexity of manufacture aredesirable.

In making improvements or modifications to the current instruments, itwould be highly desirable not to sacrifice any of the important benefitsof the [MULTIFIRE ENDO GIA * 30 and 60] instruments as compared to othercommercially available products. For example, any improvement shouldadvantageously provide a fresh knife blade for each firing of theinstrument and permit operation of the instrument with multiple sizedisposable loading units (DLU's).

SUMMARY

In accordance with the present disclosure, a surgical stapling devicefor sequentially applying a Plurality of fasteners to body tissue andsimultaneously incising tissue is provided. The surgical stapling deviceis adapted to receive disposable loading units having linear rows ofstaples having a length of between about 30 mm and 60 mm. The disposableloading units include an articulatable tool assembly which can beoperated by manipulating an articulation lever located adjacent a handleassembly of the surgical stapling device.

In addition to the handle assembly, the surgical stapling deviceincludes an elongated body defining the longitudinal axis of the device.The elongated body is operably connected to the handle assembly, forexample, by a rotatable collar or knob which is rotatable to effectrotation of the elongated body about the longitudinal axis of thedevice. The handle assembly includes a movable handle and a stationaryhandle. The movable handle is movable through an actuation stroke toapproximate a cartridge assembly and an anvil assembly, clamp tissue andeject staples from the cartridge assembly of the disposable loadingunit.

The disposable loading unit includes a proximal body portion, a mountingassembly and a tool assembly. The mounting assembly is secured to theproximal end of the tool assembly and pivotally mounted about a pivotaxis to the distal end of the proximal body portion. A support member orblow-out plate assembly is positioned on opposite sides of the pivotavis and extends between the proximal body portion and the mountingassembly. An axial drive assembly is slidably positioned between thesupport members and is translatable through the cartridge assembly toeject staples from the cartridge assembly. The support members preventoutward buckling of the axial drive assembly during actuation especiallywhen the tool assembly is articulated.

An articulation link is provided in the proximal body portion of thedisposable loading unit. A first end of the articulation link isoperably connected to an articulation assembly of the surgical staplingdevice. A second end of the articulation link is connected to themounting assembly at a point offset from the pivot axis. Thearticulation link is movable to pivot the mounting assembly about thepivot axis to articulate the tool assembly. Preferably, a protrusion isprovided in the proximal body portion of the disposable loading unit ata position to frictionally engage the articulation link. Engagementbetween the protrusion and articulation link retains the articulationlink at an axially fixed position within the proximal body portion tomaintain the tool assembly in a desired orientation until apredetermined axial force is applied to the articulation link. A recessor recesses may be provided on the articulation link at a position toreceive the protrusion to selectively retain the tool assembly at amultiplicity of articulated positions. Alternately, recesses may beprovided in the proximal body portion of the disposable loading unit andthe protrusion may be provided on the articulation link.

The disposable loading unit preferably includes a locking member whichis operably connected to the axial drive assembly. The locking memberincludes one or more extensions or protrusions which are configured tobe received within recesses formed in the proximal body portion of thedisposable loading unit. When the drive assembly is actuated toapproximate the tool assembly, the protrusions are forced from therecesses to provide an audible and/or tactile indication that the devicehas been actuated. The locking member also prevents actuation ormovement of the drive assembly during shipping.

BRIEF DESCRIPTION OF THE DRAWINGS

Various preferred embodiments of the presently disclosed surgicalstapling device are described herein with reference to the drawings:

FIG. 1 is a perspective view of one preferred embodiment of thepresently disclosed surgical stapling device;

FIG. 2 is a perspective view of another preferred embodiment of thepresently disclosed surgical stapling device;

FIG. 3 is a side view of the surgical stapling device shown in FIG. 2;

FIG. 4 is a top view of the surgical stapling device shown in FIG. 2;

FIG. 5 is a perspective view with parts separated of the handle assemblyof the surgical stapling device shown in FIG. 2;

FIG. 6 is a front side perspective view of the surgical stapling deviceshown in FIG. 2 with a housing half section, the rotatable knob, and theouter tube of the elongated body removed;

FIG. 7 is an enlarged side perspective view with portions broken away ofthe handle assembly of the surgical stapling device shown in FIG. 2 withthe housing half section removed;

FIG. 8 is an enlarged side view of the handle assembly with portionsbroken away of the surgical stapling device shown in FIG. 2 with thehousing half section removed;

FIG. 9 is a rear side perspective view of the surgical stapling deviceshown in FIG. 2 with the housing half section, the rotatable knob, andthe outer tube of the elongated body of the instrument removed;

FIG. 10 is a side vertical cross sectional view of the surgical staplingdevice shown in FIG. 2;

FIG. 11 is an exploded side perspective view of the rotatable knob andarticulation assembly of the surgical stapling device shown in FIG. 2;

FIG. 12 is a side cross sectional view of the rotatable knob,articulation assembly and elongated body of the surgical stapling deviceshown in FIG. 1;

FIG. 12A is an exploded side perspective view of the elongated body;firing rod, sensor plate and shim of the surgical stapling device shownin FIG. 1;

FIG. 13 is a side perspective view of the rack lock of the surgicalstapling device shown in FIG. 1;

FIG. 14 is a bottom perspective view of the rack lock shown in FIG. 13;

FIG. 15 is an exploded top perspective view of the articulation lever,cam cover and cam member assembly, and drive member of the surgicalstapling device shown in FIG. 1;

FIG. 16 is an exploded top perspective view of the elongated body of thesurgical stapling device shown in FIG. 2 illustrating the lock buttonand the plate and spring assembly;

FIG. 17 is a side perspective view of the elongated body of the surgicalstapling device shown in FIG. 2 with the outer tube of the elongatedbody removed;

FIG. 18 is an enlarged side view, with portions broken away, of thehandle assembly of the surgical stapling device shown in FIG. 2 with ahousing half section removed and the pawl engaging the lock rack;

FIG. 19 is a top perspective view of the pawl and plunger mechanism ofthe surgical stapling device shown in FIG. 2;

FIG. 20 is a top front perspective view of the surgical stapling deviceshown in FIG. 2 with the disposable loading unit detached from theelongated body;

FIG. 21 is a side cross sectional view of the disposable loading unit ofthe surgical stapling device shown in FIG. 2;

FIG. 22 is an exploded top perspective view of the tool assembly of thedisposable loading unit shown in FIG. 21;

FIG. 23 is an enlarged perspective view, with portions broken away, ofthe distal end of the anvil assembly of the surgical stapling deviceshown in FIG. 2 showing a plurality of staple forting cavities;

FIG. 24 is an enlarged top perspective view of the distal end of thestaple cartridge of the surgical stapling device shown in FIG. 2;

FIG. 25 is a side cross sectional view taken along a portion of sectionlines 25-25 of FIG. 24;

FIG. 26 is an enlarged perspective view of the actuation sled, thepushers and the fasteners of the surgical stapling device shown in FIG.2;

FIG. 27 is a bottom perspective view of the staple cartridge shown inFIG. 22;

FIG. 28 is an enlarged exploded top perspective view of the proximalbody portion and mounting assembly of the disposable loading unit shownin FIG. 21;

FIG. 28 a is an enlarged side perspective view of the blow out plateassembly of the surgical stapling device shown in FIG. 2;

FIG. 28 b is a top view, with portions broken away, of the proximal endof the tool assembly and the distal end of the proximal body portion ofthe disposable loading unit with the top housing half of the disposableloading unit removed;

FIG. 28 c is a side vertical cross sectional view of the proximal end ofthe tool assembly and the distal end of the proximal body portion of thedisposable loading unit of the surgical stapling device shown in FIG. 2;

FIG. 28 d is a top perspective view of the locking member of the blowout plate assembly of the surgical stapling device shown in FIG. 2;

FIG. 28 e is a front elevational view of the locking member shown inFIG. 28 d;

FIG. 28 f is a top view, with portions broken away, of the lockingmember shown in FIG. 28 d;

FIG. 28 g is a vertical cross sectional view, with portions broken away,of the proximal end of the tool assembly and the distal end of theproximal body portion of the disposable loading unit of the surgicalstapling device shown in FIG. 2;

FIG. 28 h is a transverse cross sectional view, with portions brokenaway, of the proximal end of the tool assembly and the distal end of theproximal body portion of the disposable loading unit of the surgicalstapling device shown in FIG. 2;

FIG. 29 is an enlarged perspective view, with portions broken away, ofthe mounting assembly of the disposable loading unit shown in FIG. 21mounted to a distal end portion of the proximal body portion;

FIG. 30 is a perspective view of the distal end of the proximal bodyportion and the mounting assembly of the disposable loading unit shownin FIG. 21 with the upper housing half section removed;

FIG. 31 is a perspective view of the proximal body portion and themounting assembly of the disposable loading unit shown in FIG. 21 withthe upper housing half section and outer tube removed;

FIG. 32 is a perspective view with parts separated of the axial driveassembly of the surgical stapling device shown in FIG. 2;

FIG. 33 is an enlarged perspective view of the axial drive assemblyshown in FIG. 32;

FIG. 34 is an enlarged perspective view of the distal end of the axialdrive assembly shown in FIG. 33;

FIG. 35 is an enlarged perspective view of the distal end of the axialdrive assembly shown in FIG. 32;

FIG. 36 is an enlarged perspective view of the locking device shown inFIG. 32;

FIG. 37 is an enlarged perspective view of a lower housing half of theproximal body portion of the disposable loading unit shown in FIG. 21;

FIG. 38 is a top horizontal cross sectional view of the proximal end ofthe disposable loading unit shown in FIG. 21;

FIG. 39 is a side cross sectional view of the distal end of the proximalbody portion, the mounting assembly and the proximal end of the toolassembly of the disposable loading unit shown in FIG. 21;

FIG. 40 is a perspective view of the distal end of the elongated bodyportion of the surgical stapling device shown in FIG. 2;

FIG. 41 is a perspective view of the proximal end of the disposableloading unit shown in FIG. 21;

FIG. 42 is a side view of the proximal end of the disposable loadingunit shown in FIG. 21 and the distal end of the elongated body portionof the surgical stapling device shown in FIG. 2 prior to attachment ofthe disposable loading unit to the elongated body portion;

FIG. 42 a is an enlarged perspective view of the proximal end of thedisposable loading unit shown in FIG. 21;

FIG. 43 is a side view of the proximal end of the disposable loadingunit and the distal end of the elongated body portion during attachmentof the disposable loading unit to the elongated body portion of thesurgical stapling device shown in FIG. 2;

FIG. 44 is a side cross sectional view of the distal end of theelongated body portion of the surgical stapling device shown in FIG. 2and the proximal end of the disposable loading unit shown in FIG. 21during attachment of the disposable loading unit to the elongated bodyportion;

FIG. 45 is a side view of the proximal end of the disposable loadingunit and the distal end of the elongated body portion during attachmentof the disposable loading unit to the elongated body portion;

FIG. 46 is a perspective partial cut away view, with portions brokenaway, of the proximal end of the disposable loading unit and the distalend of the elongated body portion during attachment of the disposableloading unit to the elongated body portion;

FIG. 47 is a side cross-sectional view of the surgical stapling deviceshown in FIG. 2 in the unapproximated position;

FIG. 48 is an enlarged view of the indicated area of detail shown inFIG. 47;

FIG. 49 is an enlarged view of the indicated area of detail shown inFIG. 47;

FIG. 50 is a cross-sectional view taken along section lines 50-50 shownin FIG. 49;

FIG. 51 is a side view of the handle assembly of the surgical staplingdevice shown in FIG. 2 with the handle housing and the rotatable knobshown in phantom and illustrating the sequence of operation duringattachment of a disposable loading unit to the surgical stapling device;

FIG. 52 is a top view, with portions broken away, of the cam cover andcam member assembly and sensor cap illustrating the sequence ofoperation during attachment of a disposable loading unit to theelongated body of the surgical stapling device;

FIG. 52A is a top view of the cam cover and cam member assembly andsensor cap prior to attachment of a disposable loading unit to theelongated body portion of the surgical stapling device;

FIG. 53 is a side cross-sectional view of the tool assembly of thesurgical stapling device shown in FIG. 2 in the unapproximated position;

FIG. 54 is a side cross-sectional view, with portions broken away, ofthe handle assembly of the surgical stapling device shown in FIG. 2during approximation of the surgical stapling device.

FIG. 55 is an enlarged view of the indicated area of detail shown inFIG. 54;

FIG. 56 is a side cross-sectional view of the proximal end of theproximal body portion of the disposable loading unit of the surgicalstapling device shown in FIG. 2 after the device has been approximated;

FIG. 57 is a side cross sectional view of the tool assembly of thedisposable loading unit of the surgical stapling device shown in FIG. 2in the approximated position;

FIG. 58 is a side cross sectional view of the handle assembly of thesurgical stapling device shown in FIG. 2 in the approximated positionwith the handle in the non-compressed position;

FIG. 59 is a cross-sectional view taken along a portion of section lines59-59 of FIG. 58;

FIG. 60 is a side cross sectional view of the handle assembly of thesurgical stapling device shown in FIG. 2 with the plunger disengagedfrom the vertical pawl;

FIG. 61 is a cross-sectional view taken along a portion of section lines61-61 of FIG. 60;

FIG. 62 is an enlarged view of the indicated area of detail shown inFIG. 60;

FIG. 63 is a side cross-sectional view of the handle assembly of thesurgical stapling device shown in FIG. 2 during the firing stroke of thesurgical stapling device;

FIG. 64 is a cross sectional view taken along a portion of section lines64-64 of FIG. 63;

FIG. 65 is an enlarged view of the indicated area of detail shown inFIG. 63;

FIG. 66 is a cross-sectional view of the distal end of the tool assemblyduring the firing stroke of surgical stapling device;

FIG. 67 is a side cross-sectional view of the tool assembly of thesurgical stapling device shown in FIG. 2 after completion of the firingstroke;

FIG. 68 is a side view of the handle assembly of the surgical staplingdevice shown in FIG. 2 during retraction of the actuation shaft;

FIG. 69 is a top view of the rotatable knob and articulation mechanismof the surgical stapling device shown in FIG. 2 with the tool assemblyarticulated in a first direction with the rotatable knob and thearticulation lever shown in phantom;

FIG. 70 is a top view of the rotatable knob and articulation mechanismsof the surgical stapling device shown in FIG. 2 with the tool assemblyarticulated in a second direction;

FIG. 71 is a side perspective view of the articulation mechanism of thesurgical stapling device shown in FIG. 2;

FIG. 72 is a top view of the rotatable knob and articulation mechanismof surgical stapling device shown in FIG. 2 with the rotatable knob andarticulation lever shown in phantom;

FIG. 73 is a top view of the distal end of the disposable loading unitprior to articulation of the tool assembly;

FIG. 74 is a top view of the distal end of the disposable loading unitduring articulation of the tool assembly in a first direction;

FIG. 75 is a top view of the distal end of the disposable loading unitshown in FIG. 21 during articulation of the tool assembly in a seconddirection;

FIG. 76 is a side perspective view of the surgical stapling device shownin FIG. 2 with the tool assembly articulated in a first direction;

FIG. 77 is a side perspective view of the surgical stapling device shownin FIG. 2 with the tool assembly articulated in a second direction;

FIG. 78 is a side partial cross-sectional view of a portion of thedisposable loading unit shown in FIG. 21 during retraction of thelocking device;

FIG. 79 is a side partial cross-sectional view of a portion of thedisposable loading unit shown in FIG. 21 with the locking device in thelocked position;

FIG. 80 is an enlarged exploded perspective view of the proximal bodyportion and mounting assembly of another preferred embodiment of thedisposable loading unit;

FIG. 81 is an enlarged side perspective view of the blow out plateassembly of the disposable loading unit shown in FIG. 80;

FIG. 82 is a top view, with portions broken away, of the proximal end ofthe tool assembly and the distal end of the proximal body portion of thedisposable loading unit shown in FIG. 80 with the top housing half ofthe disposable loading unit removed;

FIG. 83 is a side cross-sectional view of the proximal end of the toolassembly and the distal end of the proximal body portion of thedisposable loading unit shown in FIG. 80;

FIG. 84A is a top perspective view of the locking member of the blow outplate assembly of the disposable loading unit shown in FIG. 80;

FIG. 84B is a front elevational view of the locking member shown in FIG.84A;

FIG. 84C is a top view of the locking member shown in FIG. 84A;

FIG. 85 is a side cross-sectional view of the proximal end of the toolassembly and the distal end of the proximal body portion of thedisposable loading unit shown in FIG. 80;

FIG. 86 is a transverse cross-sectional view of the proximal end of thetool assembly and the distal end of the proximal body portion of thedisposable loading unit shown in FIG. 80;

FIG. 87 is a perspective view of the distal end of the proximal bodyportion and the mounting assembly of the disposable loading unit shownin FIG. 80;

FIG. 88 is a perspective view of the distal end of the proximal bodyportion and mounting assembly of the disposable loading unit shown inFIG. 80 with the upper housing half removed;

FIG. 89 is a perspective view of the distal end of the proximal bodyportion with the upper housing half section removed;

FIG. 90 is a perspective view of the upper housing half of the proximalbody portion of the disposable loading unit shown in FIG. 80;

FIG. 90A is an enlarged view of the indicated area of detail shown inFIG. 90;

FIG. 91 is a perspective view of the articulation link of the disposableloading unit shown in FIG. 80;

FIG. 91A is an enlarged view of the indicated area of detail shown inFIG. 91;

FIG. 92 is a side view of the upper housing half and the articulationlink of the disposable loading unit shown in FIG. 80;

FIG. 93 is a side view of the upper housing half and articulation linkof the disposable loading unit shown in FIG. 80 as the articulation linkis advanced to articulate the tool assembly;

FIG. 94 is a perspective view of the locking member of the disposableloading unit shown in FIG. 80;

FIG. 95 is a perspective view of the proximal end of the proximal bodyportion of the disposable loading unit shown in FIG. 80; and

FIG. 96 is a top view of the proximal end of the proximal body portionof the disposable loading unit shown in FIG. 80.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Preferred embodiments of the presently disclosed surgical staplingdevice will now be described in detail with reference to the drawings inwhich like reference numerals designate identical or correspondingelements in each of the several views.

In the description that follows, the term “proximal”, as is traditional,will refer to the end of the stapling device which is closest to theoperator, while the term distal will refer to the end of the devicewhich is furthest from the operator.

FIGS. 1-4 illustrate one preferred embodiment of the presently disclosedsurgical stapling device shown generally as 10. Briefly, surgicalstapling device 10 includes a handle assembly 12 and an elongated body14. As illustrated in FIGS. 1 and 2, the length of elongated body 14 mayvary to suit a particular surgical procedure. A disposable loading unitor DLU 16 is releasably secured to a distal end of elongated body 14.DLU 16 includes a proximal body portion 18, which forms an extension ofelongated body 14, and a distal tool assembly 20 including a cartridgeassembly 22 and an anvil assembly 24. Tool assembly 20 is pivotablyconnected to body 18 about an axis substantially perpendicular to thelongitudinal axis of elongated body 14. Cartridge assembly 22 houses aplurality of staples. Anvil assembly 24 is movable in relation tocartridge assembly 22 between an open position spaced from cartridgeassembly 22 and an approximated or clamped position in juxtaposedalignment with cartridge assembly 24. Preferably, the staples are housedin cartridge assembly 22 to apply linear rows of staples having a lengthmeasuring from about 30 mm to about 60 mm, although other stapleconfigurations and lengths are envisioned.

Handle assembly 12 includes a stationary handle member 26, a movablehandle or trigger 28 and a barrel portion 30. A rotatable member 32 ispreferably rotatably mounted to the forward end of barrel portion 30 andsecured to elongated body 14 to facilitate rotation of elongated body 14in relation to handle assembly 12. An articulation lever 122 issupported on a distal portion of barrel portion 30 and is operable, in amanner to be described hereafter, to effect articulation of toolassembly 20 with respect to body portion 18 of DLU 16. A pair of returnknobs 36 are movably supported along barrel portion 30 to effectmovement of surgical stapling device 10 from an advanced position to aretracted position, as will be described in detail below.

Referring to FIGS. 5-8, handle assembly 12 includes a housing 38, whichis preferably formed from plastic molded housing half-sections 38 a and38 b. Alternately, other materials may be used to form the housingincluding metals, e.g., stainless steel. Housing 38 forms stationaryhandle 26 and barrel portion 30 of handle assembly 12 (see FIG. 1).Movable handle 28 is rotatably supported between housing half-sections38 a and 38 b about a cylindrical member 40 which is received within anopening 41 in movable handle 28. A biasing member 42, which ispreferably a torsion spring, urges movable handle 28 away fromstationary handle 26 to a non-compressed position. Movable handle 28includes a pair of throughbores 46 dimensioned to receive a pivot member47. A pawl 48 is rotatably supported on pivot member 47 and is biased bya spring 50 towards actuation shaft 52.

Actuation shaft 52 is slidably supported between retracted and advancedpositions within barrel portion 30 of housing 38 and includes a distalend defining a recess 54 configured to rotatably receive the proximalend 56 of firing rod 58. A spring biased retract arm 57 is rotatablymounted between housing half-sections 38 a and 38 b and includes anextension 57 a. Extension 57 a is positioned within a slot 59 (FIG. 5)formed in actuation shaft 52 to urge actuation shaft 52 to a fullyretracted position. Actuation shaft 52 includes a toothed rack 60. Pawl48 has an engagement finger 62 which is biased by spring 50 towardstoothed rack 60 of actuation shaft 52. When movable handle 28 isactuated, i.e., is compressed towards stationary handle 26 against thebias of spring 42, engagement finger 62 of pawl 48 engages toothed rack60 of actuation shaft 52 to advance actuation shaft 52 and firing rod 58distally. Firing rod 58 preferably includes a distal end which is formedfrom stainless steel and the remaining portion (approximately 90%)formed from aluminum. The two parts may be press fit together.Alternately, firing rod 58 may be formed from a single material or anymaterial or materials having the requisite strength requirements.

Referring to FIGS. 5, 13 and 14, rack lock 64 including pivot members 66is pivotably supported about pivot members 66 between housinghalf-sections 38 a and 38 b. A biasing member 67 a, which is preferablya torsion spring, is positioned to urge rack lock 64 in a clockwisedirection as viewed in FIG. 5. Rack lock 64 includes blocking portion 64a which is positioned within housing 38 to prevent engagement betweenengagement finger 62 of pawl 48 and toothed rack 60 of actuation shaft52 when a DLU 16 is not attached to stapling device 10 and movablehandle 28 is compressed (See FIG. 18). When a DLU is attached to device10, rack lock 64 is pivoted, in a manner to be described below, to moveblocking portion 64 a of rack lock 64 to a non-blocking position inwhich finger 62 of pawl 48 is free to engage toothed rack 60 ofactuation shaft 52. Rack lock 64 also includes a locking portion 64 bwhich is positioned Within a recess 52 a of actuation shaft 52 toprevent axial movement of actuation shaft 52 until after a DLU 16(FIG. 1) has been attached to the device.

Referring to FIGS. 5 and 19, a vertical pawl 69 is slidably positionedin a slot 68 defined between housing half-sections 38 a and 38 b.Vertical pawl 69 is movable from an extended or upward position in whichthe tip 69 a of pawl 69 engages a notch 67 formed in the distal end ofactuation shaft 52, to a retracted or downward position in which tip 69a of pawl 69 is spaced from actuation shaft 52. A spring 70 supportedbetween housing half-sections 38 a and 38 b is positioned to urge pawl69 to the extended position. In the extended position, pawl 69 preventsadvancement of actuation shaft 52 to prevent firing of stapling device10.

A plunger 72 is reciprocably supported between spaced cylindricalchannels 74 formed in housing half-sections 38 a and 38 b. Plunger 72includes a cam member 76. A spring 78 is positioned on each end ofplunger 72 within cylindrical channels 74. Springs 78 urge plunger 72 toa position wherein cam member 76 is centrally positioned between a pairof cam surfaces 80 formed on vertical pawl 69. Each cam surface 80 has arecess 82 a (FIG. 19) formed therein for releasably receiving cam member76 of plunger 72.

Each end 72 a (FIG. 1) of plunger 72 extends through stationary handle26 and can be pressed against the bias of one of springs 78 to force cammember 76 into engagement with a respective one of cam surfaces 80 onvertical pawl 66. When cam member 76 is moved into engagement with oneof cam surfaces 80, vertical pawl 69 is urged from the extended positionto the retracted position to move tip 69 a of vertical pawl 69 out ofnotch 67 of actuator shaft 52. See FIGS. 61 and 62. Stapling device 10is now in a fire-ready position. The positioning of tip 76 a of cammember 76 in recess 80 a of a respective cam surface 80 retains verticalpawl in the retracted position to maintain device 10 in the fire-readyposition.

Retraction Mechanism

A retraction mechanism which includes return knobs 36 (FIG. 1) isconnected to the proximal end of actuation shaft 52 by a coupling rod82. Coupling rod 82 has right and left engagement portions 82 a and 82 bwhich extend through elongated slots 83 (FIG. 1) formed in housinghalf-sections 38 a and 38 b and are configured to receive return knobs36. A central portion 82 c of coupling rod 82 is dimensioned to beslidably received within slots 84 formed in the proximal end ofactuation shaft 52. A release plate 86 is supported on one side ofactuation shaft 52 by a pair of pins 88. Pins 88 are positioned withinangled cam slots 90 formed through release plate 86. Coupling rod 82extends through an opening 92 formed in the proximal end of releaseplate 86.

In use, when knobs 36 are pulled rearwardly by a surgeon, coupling rod82 initially moves release plate 86 rearwardly in relation to actuationshaft 52 as rod 82 slides in slots 84 of actuation shaft 52. As thisoccurs, pins 88 cam release plate 86 downwardly to a position coveringtoothed rack 60 of actuation shaft 52 to disengage finger 62 of pawl 48from toothed rack 60. When coupling rod 82 is pulled rearwardly to aposition at which it engages the back end 84 a of slots 84, additionalrearward movement knobs 36 effect proximal movement of actuation shaft52 and firing rod 58.

A hook 96 is supported in a slot 98 formed in a top surface of actuationshaft 52. Hook 96 includes a throughbore 96 a dimensioned to receivecoupling rod 82. A forward end of hook 96 includes an upturned portion98 configured to receive one looped end 100 a of spring 100. Theopposite end of spring 100 includes a loop 100 b dimensioned to receivea post 102 formed on, actuation shaft 52. Spring 100 is maintained intension to urge coupling rod 82 towards the forward end of slots 84 inactuation shaft 52. When coupling rod 82 is positioned at the forwardend of slots 84 of actuation shaft 52, release plate 86 is held orcaromed in a raised position above toothed rack 60 of actuation shaft 52(FIG. 8).

Rotation Assembly

Referring to FIGS. 5 and 10-12, rotatable knob 32 is preferably formedfrom molded plastic half-sections 32 a and 32 b, although othermaterials, e.g., metals, and manufacturing methods are envisioned. Theinner surface of the proximal end of rotatable knob 32 includes anannular ring 106 dimensioned to be received within an annular slot 108formed in the forward end of barrel portion 30 of handle assembly 12 torotatably attach knob 32 to handle assembly 12. An O-ring 107 ispositioned between annular ring 106 and handle assembly 12 to create afriction drag between knob 32 and handle assembly 12. The friction dragprevents free rotation of knob 32 in relation to handle assembly 12. Theouter surface of the proximal end of rotatable knob 32 includes ascalloped configuration 110 to facilitate gripping of rotatable knob 32.The inner surface of the distal end of rotatable knob 32 defines anopening 112 and includes a protrusion 114 configured and dimensioned tobe received within openings 116 formed in the proximal end of elongatedbody 14. The central portion of rotatable knob 32 includes a post 118and defines a transverse channel 120 configured to operably receive thearticulation mechanism of the stapling device 10 as will be described indetail below.

Articulation Mechanism

Referring also to FIG. 15, the articulation mechanism of the presentlydisclosed stapling device 10 includes an articulation lever 122, a cammember 124, a cam cover 126, a drive member 128 and an articulationmember or link 130 (FIG. 11). Articulation lever 122 is rotatablysecured to post 118 of rotatable knob 32 by a lever pin 132. Althoughlever pin 132 is shown as a separate element from lever 122, it isenvisioned that pin 132 may be integrally formed with lever 122. Aprojection 134 (FIG. 12) extends downwardly from a bottom surface oflever 122 and is received within an elongated slot 136 formed in camcover 126. Cam member 124 is fixedly secured to the base of cam cover126 by a pair of press-fit projections 126 a (FIG. 15) which arereceived within openings 124 a formed in cam member 124. Alternately,other known fastening techniques including screws, snap-fit connectors,welding; interlocking members, etc., may be used to secure cam cover 126to cam member 124. Cam cover 126 and cam member 124 define an assemblyhaving front and rear ledges 140. The assembly is dimensioned to beslidably positioned in transverse channel 120. Ledges 140 are receivedwithin recesses 142 formed in channel 120 to prevent separation of thecam cover and cam member assembly from channel 120 and to limit the camcover and cam member to linear movement. Preferably, cam cover 126 isformed of plastic and cam member 124 is formed of a metal, e.g.,stainless steel. Alternately, other materials of construction areenvisioned.

Transverse channel 120 of rotatable knob 32 includes a longitudinal slot144 extending therethrough. Cam member 124 has a stepped cam slot 146formed therethrough. A cam pin 148 includes a first projection 150 whichextends upwardly as viewed in FIG. 12 through longitudinal slot 144 andis received within stepped cam slot 146 of cam member 124. Cam pin 148also includes a second projection 152 which extends downwardly as viewedin FIG. 12 into an opening 154 formed in drive member 128.

Drive member 128 includes a body portion 128 a including opening 154 anda longitudinal extension 128 b. An engagement member 156 is formed atthe distal end of longitudinal extension 128 b. Engagement member 156 isconfigured to be received within an opening 158 formed in the proximalend of articulation link 130. The distal end of articulation link 130also includes engagement structure 160 for engaging an articulation linkpositioned within a DLU 16 (FIG. 1) as will be described in detailbelow.

In operation, when articulation lever 122 is rotated about lever pin132, projection 134 causes the cam cover 126 and cam member 124 assemblyto move across transverse channel 120. Movement of cam member 124 acrosstransverse channel 124 causes stepped cam slot 146 to move in relationto first projection 150 of cam pin 148, thus causing cam pin 148 to movethrough longitudinal slot 144. Longitudinal movement of cam pin 148effects corresponding longitudinal movement of drive member 128 andarticulation link 130. The interconnection of articulation link 130 andthe articulation structure within DLU 16 will be described in detailbelow.

DLU Sensor Mechanism

Referring to FIGS. 5-12, surgical stapling device 10 includes a sensormechanism for determining if a DLU 16 has been attached to elongatedbody 14. The sensor mechanism includes a sensor plate 170 (FIG. 5), arack lock release member 172 and a sensor cap 174 (FIG. 11). Whenelongated body 14 is of an extended length, a sensor tube (not shown)may be positioned between sensor plate 170 and sensor cap 174 totranslate movement of sensor plate 170 to sensor cap 174. Sensor plate170 is slidably positioned along a flat 58 a formed on firing rod 58 andincludes a distal end 170 a and a proximal end 170 b. In an alternateembodiment, a shim or spacer 170 c (FIG. 12A) may be positioned onsensor plate 170 between an inner wall of elongated body 14. Shim 170 cfunctions to maintain sensor plate 170 in slidable contact with firingrod 58 and in alignment with sensor cap 174, thus preventing sensorplate 170 as from overriding and losing axial contact with sensor cap174. Although shown as being a separate element from sensor plate 170,shim 170 c may be integrally or monolithically formed with sensor plate170. Sensor cap 174 is slidably positioned within rotatable knob 32between advanced and retracted positions and includes an articulationlocking tab 174 a, a proximal flange 174 b, and an upper flat surface174 c, (See FIG. 11.) Upper flat surface 174 c is positioned withinrotatable knob 32 beneath transverse channel 120 such that tab 174 aextends upwardly through an opening in knob 32 into a cutout 176 formedin cam cover 126 and cam member 124. When sensor cap 174 is in theadvanced position, tab 174 a is positioned within cutout 176 to preventmovement of cam member 124 along transverse channel 120 to preventarticulation of surgical stapling device 10. When sensor cap 174 ismoved to the retracted position, in a manner to be described below, tab174 a is moved proximally from cutout 176 to permit movement of cammember 124 along transverse channel 120 and thus, permit articulation ofsurgical stapling device 10.

Rack lock release member 172 includes a distal end 172 a configured toengage flange 174 b of sensor cap 174 and a proximal end 172 bpositioned adjacent rack lock 64. A biasing member 180, preferably acoil spring, is positioned within a slot 172 c formed in rack lockrelease member 172 between one end of slot 172 c and a finger (notshown) extending into slot 172 c from housing assembly 12 to urge lockrack release member 172 distally and thus urge sensor cap 174 and sensorplate 170 distally to the advanced position.

In operation, when a DLU is not attached to surgical stapling device 10,biasing member 180 maintains lock rack release member 172, sensor cap174 and sensor plate 170 in their advanced positions. As discussedabove, in the advanced position, sensor cap locking tab 174 a ispositioned within cam member cutout 176 to prevent articulation ofsurgical stapling device 10. In the advanced position, lock rack releasemember 172 is also spaced from rack look 64 such that locking portion 64b of rack lock 64 is positioned within a recess 52 a formed in actuationshaft 52 to lock actuation shaft 52 in a fixed retracted position andblocking portion 64 a of rack lock 64 is positioned to preventengagement of pawl 48 and toothed rack 60 of actuation shaft 52. When aDLU 16 is secured to the distal end of elongated body 14, the proximalend of the DLU engages distal end 170 a of sensor plate 170 to movesensor plate 170 proximally. Proximal movement of sensor plate 170effects corresponding proximal movement of sensor cap 174 and lock rackrelease member 172. Proximal movement of sensor cap 174 to the retractedposition removes locking tab 174 a from cam member cutout 176 to permitselective articulation of stapling device 10. When lock rack releasemember 172 is moved proximally, the proximal end 172 b of member 172abuts against a bottom surface of rack lock 64 to pivot locking portion64 b of rack lock 64 upwardly out of recess 52 a of actuation shaft 52to facilitate advancement of actuation shaft 52 and to pivot blockingportion 64 a of rack lock 64 to a position not obstructing engagementbetween engagement finger 62 of pawl 48 and toothed rack 60 of actuationshaft 52.

Referring to FIGS. 11, 12, 16 and 17, elongated body 14 includes a bodyportion 14 a, a body cover 14 b and an end cap 14 c. Body cover 14 b ispositioned about body portion 14 a and end cap 14 c is secured to theproximal end of body portion 14 a. Elongated body 14, as discussedabove, is secured between rotatable knob half-sections 32 a and 32 b viaprotrusions 114 formed on half-sections 32 a and 32 b positioned withinopenings 116 formed in the proximal end of body portion 14 a (openings116 a are also formed through end cap 14 c). Elongated body 14 defines alongitudinal throughbore through which firing rod 58, sensor plate 170,and articulation link 130 extend. As discussed above, when elongatedbody 14 is of an extended length, a sensor tube may also be providedwithin elongated body 14.

A lock button 190 and a plate and spring assembly 192 are supported inrecesses formed in elongated body 14. Lock button 190 is slidablypositioned distally of spring assembly 192 (See FIG. 12) adjacent thedistal end of elongated body 14 and includes a distal engagement finger190 a and a proximal tapered abutment surface 190 b. Finger 190 a ispositioned to engage the proximal end of a DLU 16 (FIG. 1) duringattachment of the DLU 16 to elongated body 14. A biasing member 194 isprovided to urge lock button 190 in a distal direction. Plate and springassembly 192 includes a plate 192 a having a blocking portion 192 b anda spring member 192 c. Spring member 192 c is preferably a leaf springwhich is secured directly to plate 192 a. Alternately, otherconfigurations are envisioned, e.g., the plate and the spring member areseparate elements. Blocking portion 192 b is positioned adjacent to anotch 196 formed in firing rod 58 (FIG. 12).

When a DLU is attached to the distal end of elongated body 14, as willbe described in further detail below, the DLU is inserted into elongatedbody 14 and rotated in relation to elongated body 14 to lock DLU 16thereon. During insertion of DLU 16 into elongated body 14, the proximalend of DLU 16 engages finger 190 a of look button 190 and forces lockbutton 190 proximally against the bias of spring 194 such that abutmentsurface 190 b of lock button 190 engages plate 192 a of assembly 192.Engagement between abutment surface 190 b and plate 192 a moves blockingportion 192 b, against the bias of spring member 192 c, into notch 196of firing rod 58 to lock firing rod 58 in an axially fixed position toprevent firing of the device until the DLU has been rotated to thelocked position. When the DLU is rotated to the locked position, spring194 returns lock button 190 to its distal position spaced from plate 192a and spring member 192 c urges blocking portion 192 b from notch 196 offiring rod 58 to permit axial movement of firing rod 58. Preferably,movement of lock button 190 to its distal position provides an audibleindication that the DLU is locked on elongated body 14.

FIG. 20 illustrates surgical stapling device 10 and a DLU 16 prior toattachment of the DLU to elongated body 14 of device 10. As discussedabove, prior to attachment of DLU 16 to device 10, movable handle 16 isrendered inoperable by rack lock 64 which prevents pawl 48 from engagingtoothed rack 60 of actuation shaft 52 and locks actuation shaft 52 in afixed axial position.

Referring also to FIG. 21, disposable loading unit 16 includes proximalbody portion 18 which is configured to releasably engage the distal endof elongated body 14, and distal tool assembly 20 which is pivotallysecured to the distal end of body portion 18 by a mounting assembly 202(FIG. 28).

Referring also to FIGS. 22-28, tool assembly 20 includes anvil assembly24 and cartridge assembly 22 (FIG. 22). Anvil assembly 24 has anvilportion 204 having a plurality of staple deforming concavities 206 (FIG.23) and a cover plate 208 secured to a top surface of anvil portion 204to define a cavity 210 (FIG. 25) therebetween. Cover plate 208 isprovided to prevent pinching of tissue during approximation and firingof stapling device 10. Cavity 210 is dimensioned to slidably receive adistal end of an axial drive assembly 212 (See FIG. 28). A longitudinalslot 214 extends through anvil portion 204 to facilitate passage ofretention flange 284 (FIG. 28) of axial drive assembly 212 through anvilcavity 210. A camming surface 209 formed on anvil portion 204 ispositioned to be engaged by axial drive assembly 212 to facilitateapproximation of the anvil and cartridge assemblies and clamping oftissue 198 (FIG. 25). A pair of pivot members 211 formed on anvilportion 204 are positioned within slots 213 formed in carrier 216 toguide the anvil portion between the spaced and approximated positions. Apair of stabilizing members 215 engage a respective shoulder 217 formedon carrier 216 to prevent anvil portion 204 from sliding axiallyrelative to staple cartridge 220 as camming surface 209 is pivoted aboutpivot members 211.

Cartridge assembly 22 includes carrier 216 which defines an elongatedsupport channel 218. Elongated support channel 218 is dimensioned andconfigured to receive a staple cartridge 220. Corresponding tabs 222 andslots 224 formed along staple cartridge 220 and elongated supportchannel 218, respectively, function to retain staple cartridge 220 at afixed location within support channel 218. A pair of support struts 223formed on staple cartridge 220 are positioned to rest on side walls ofcarrier 216 to further stabilize staple cartridge 220 within supportchannel 218.

Staple cartridge 220 includes retention slots 225 for receiving aplurality of fasteners 226 and pushers 228. A plurality of spaced apartlongitudinal slots 230 extend through staple cartridge 220 toaccommodate upstanding cam wedges 232 of actuation sled 234. A centrallongitudinal slot 282 extends along the length of staple cartridge 220to facilitate passage of a knife blade 280 (FIG. 28). During operationof surgical stapler 10, actuation sled 234 translates throughlongitudinal slots 230 of staple cartridge 220 to advance cam wedges 232into sequential contact with pushers 228, to cause pushers 228 totranslate vertically within slots 224 and urge fasteners 226 from slots224 into the staple deforming cavities 206 of anvil assembly 20.

Referring to FIGS. 28 and 29, mounting assembly 202 includes upper andlower mounting portions 236 and 238. Each mounting portion includes athreaded bore 240 on each side thereof dimensioned to receive threadedbolts 242 (See FIG. 22) for securing the proximal end of carrier 216thereto. A pair of centrally located pivot members 244 extends betweenupper and lower mounting portions 236 and 238 through a pair of couplingmembers 246 which engage the distal end of body portion 18.Coupling/members 246 each include an interlocking proximal portion 248configured to be received in grooves 249 formed in the proximal end ofbody portion 18 to retain mounting assembly 202 and body portion 18 in alongitudinally fixed position in relation thereto.

Body portion 18 of disposable loading unit 16 includes an upper housinghalf 250 and a lower housing half 252 contained within an outer casing251. The proximal end of housing half 250 includes engagement lugs 254for releasably engaging elongated body 14 in a bayonet coupling typefashion. The proximal end of housing half 250 also includes as insertiontip 193 which will be discussed in further detail below. Housing halves250 and 252 define a channel 253 for slidably receiving axial driveassembly 212. A second articulation link 256 is dimensioned to beslidably positioned within a slot 258 formed between housing halves 250and 252. A pair of blow out plates 255 are positioned adjacent thedistal end of body portion 18 adjacent the distal end of axial driveassembly 212 to prevent outward bulging of drive assembly 212 duringarticulation and firing of tool assembly 20.

FIGS. 28 a-h illustrate an alternate embodiment of blow out plates 255shown generally as blow out plate assembly 254 a. Blow out plateassembly 254 a includes a flexible body 255 a and an H-block 256 a.Flexible body 255 a has a proximal end 258 a and a distal end 260 a. Thedistal and proximal ends each include a retaining portion 258 b and 260b, respectively. Retaining portion 258 b is configured to be and isfixedly received and engaged within recesses 250 a and/or 252 a formedin respective upper and/or lower housing halves 250 and 252 of DLU 16(FIG. 28 b). Retaining section 260 b includes a pair of J-shapedattachment members configured to be and which are fixedly received andengaged within recesses 236 a and 238 a formed in respective upperand/or lower mounting portions 236 and 238 of mounting assembly 202. Thetips 260 c of J-shaped attachment members are angled to engage and lockinto recesses 236 a and 238 b (FIG. 28 g), and are preferably press-fitinto the walls that form recesses. A locking member 268 a (FIGS. 28 d-f)includes an H-shaped body having a pair of legs 266 a and a central web267 a. Each leg 266 a includes an elongated retaining protrusion 270 ahaving tapered ends. Locking member 268 a is dimensioned to be and ispress fit within recesses 250 a and 252 a formed in respective upper andlower housing halves 250 and 252 of DLU 16 adjacent retaining section258 b to fixedly secure the retaining section 258 b within the recesses.A central portion of blow out plate assembly 254 a includes a pair ofsubstantially U-shaped spring portions 262 a. U-shaped spring portion262 a allows the central portion of body 255 a to flex slightlyoutwardly to accommodate sliding and articulating movement of driveassembly 212 (FIG. 28) when tool assembly 20 is actuated, i.e.,approximated or fired. As shown in FIG. 28 h, H-block 256A is positionedwith a small gap about spring portions 262 a to limit the extent towhich U-shaped spring portions 262 a are able to flex to preventbuckling of the blow out plate assembly 254 a and drive assembly 212during actuation of device 10. A blow-out plate assembly 254 a ispositioned on each side of drive assembly 212 to prevent outwardbuckling of drive assembly 212 during actuation of device 10, includingwhen device 10 is articulated.

Referring to FIGS. 30 and 31, second articulation link 256 includes atleast one elongated metallic plate. Preferably, two or more metallicplates are stacked to form link 256. The proximal end of articulationlink 256 includes a hook portion 258 configured to engage articulationlink 130 (See FIG. 6) and the distal end includes a loop 260 dimensionedto engage a projection 262 formed on mounting portion 238 of mountingassembly 202. Projection 262 is laterally offset from pivot pin 244 suchthat linear movement of second articulation link 256 causes mountingassembly 202 to pivot about pivot pins 244 to articulate tool assembly20 in relation to body portion 18.

Referring also to FIGS. 32-35 and 39, axial drive assembly 212 includesan elongated drive beam 266 including a distal working head 268 and aproximal engagement section 270. Drive beam 266 may be constructed froma single sheet of material or, preferably, multiple stacked sheets.Engagement section 270 includes a pair of engagement fingers 270 a and270 b which are dimensioned and configured to mountingly engage a pairof corresponding retention slots 272 a and 272 b formed in drive member272. Drive member 272 includes a proximal porthole 274 configured toreceive the distal end 276 of firing rod 58 (See FIG. 12) when theproximal end of disposable loading unit 16 is engaged with elongatedbody 14 of surgical stapling apparatus 10.

The distal end of working head 268 of chive beam 266 is defined by avertical support strut 278 (FIG. 32) which supports a knife blade 280,and an abutment surface 283 which engages the central portion ofactuation sled 234 during a stapling procedure. Surface 285 is locatedat the base of surface 283 and is configured to receive a support member287 (FIG. 39) which is slidably positioned along the bottom of thestaple cartridge 220. Knife blade 280 is positioned to translateslightly behind actuation sled 234 through a central longitudinal slot282 in staple cartridge 220 (FIG. 22) to form an incision between rowsof stapled body tissue. A retention flange 284 projects distally fromvertical strut 278 and supports a cylindrical cam roller 286 at itsdistal end. Cain roller 286 is dimensioned and configured to engage camsurface 209 on anvil body 204 to clamp anvil portion 204 against bodytissue.

Referring also to FIGS. 21 and 36-38, a locking device 288 is pivotallysecured to drive member 270 about a pivot pin 290. Locking device 288includes a pair of elongate glides 292 and 294 which define a channel296. A web 298 joins a portion of the upper surfaces of glides 292 and294, and is configured and dimensioned to fit within elongated slot 298formed in drive beam 266 at a position distal of drive member 272.Horizontal cams 300 and 302 extend from glides 292 and 294 respectively,and are accommodated along an inner surface of lower housing half 252.As best shown in FIG. 38, a torsion spring 304 is positioned adjacentdrive member 270 and engages horizontal cams 300 and 302 (FIG. 36) oflocking device 288 to normally bias locking device 288 downward towardlower housing half 252 onto ledge 310. Locking device 288 translatesthrough housing portion 200 with axial drive assembly 212. Operation oflocking device 288 will be described below.

FIGS. 80-96 illustrate an alternate embodiment of the presentlydisclosed disposable loading unit. As discussed above with respect toDLU 16, DLU 516 includes a mounting assembly 522. Mounting assembly 522includes upper and lower mounting portions 580 and 582. A centrallylocated pivot member 584 extends from each of upper and lower mountingportions 580 and 582 through an opening 586 a formed in a couplingmember 586 which engages the distal end of proximal body portion 518.Coupling members 586 each include an interlocking proximal portion 588configured to be received in grooves 590 formed in the proximal end ofbody portion 518 to retain mounting assembly 522 and body portion 518 ina longitudinally fixed position in relation to each other.

Body portion 518 of disposable loading unit 516 (FIG. 21) includes anupper housing half 592 and a lower housing half 594 contained within anouter casing 596. The proximal end of housing half 592 includesengagement lugs 596 for releasably engaging the distal end of instrument10 (FIG. 20) and an insertion tip 598. Lugs 596 form a bayonet typecoupling with the distal end of instrument 10. Housing halves 592 and594 define a channel 600 for slidably receiving axial drive assembly536. An articulation link 602 is dimensioned to be slidably positionedwithin a slot 604 formed housing upper and lower housing halves 592 and594. A pair of blow out plate assemblies 606 are positioned adjacent thedistal end of body portion 518 adjacent the distal end of axial driveassembly 536 to prevent outward buckling and/or bulging of driveassembly 536 during articulation and firing of tool assembly 520.

FIGS. 81-89 illustrate details of blowout plate assemblies 606. Eachblow out plate assembly 606 includes a laterally flexible body 610 andan H-block 612. Flexible body 610 has a proximal end 614 and a distalend 616. The distal and proximal ends each include a retaining portion618 and 620, respectively. Retaining portion 618 is configured to be andis fixedly received and engaged within recesses 621 and/or 622 formed inupper and/or lower housing halves 592 and 594 of DLU 16 (FIGS. 21, 82,85). Retaining section 620 includes a pair of J-shaped attachmentmembers configured to be and which are fixedly received and engagedwithin recesses 623 and 624 formed in upper and/or lower mountingportions 580 and 582 of mounting assembly 522. The tips 630 of J-shapedattachment members are angled to engage and lock into recesses 623 and624 (FIG. 82), and are preferably press-fit into the walls that form therecesses.

A locking member 634 (FIGS. 84 a-84 c) includes an H-shaped body havinga pair of legs 636 and a central web 638. Bach leg 636 includes anelongated retaining protrusion 640 having tapered ends. Locking member634 is dimensioned to be and is press fit within recesses 621 and 622formed in upper and lower housing halves 592 and 594 (FIG. 83) of DLU 16(FIG. 21) adjacent retaining section 618 to fixedly secure retainingsection 618 within the recesses. A central portion of blow out plateassembly 606 includes spring portion or section which preferablyincludes a pair of substantially U-shaped spring portions 644. U-shapedspring portion 644 allows the central portion of body 610 to lengthenaxially and flex slightly outwardly relative to or of the longitudinalaxis to accommodate sliding and articulating movement of drive assembly536 (FIG. 80) including when tool assembly 20 (FIG. 21) is actuated,i.e., approximated or fired. By providing a support member which iscapable of axially lengthening, binding of the drive assembly due to thedifference in radius of curvature along the inner and outer surfaces ofthe drive assembly adjacent the pivot axis is substantially reduced.

As shown in FIG. 81, a limit member, which is preferably formed as anH-block 612, is positioned with a small gap about spring portions 644 tolimit the extent to which U-shaped spring portions 644 are able to flexto prevent binding and/or buckling of the blow out plate assembly 606and drive assembly 536 during actuation of device 510. A blow-out plateassembly 606 is positioned on each side of drive assembly 536 adjacentthe pivot axis of tool assembly 512 to prevent outward buckling and/orbinding of drive assembly 536 during actuation of device 510, includingwhen device 510 is articulated.

Referring to FIGS. 80 and 87-93, an articulation link 602 includes atleast one elongated metallic plate. Preferably, two or more metallicplates are stacked to form link 602. The proximal end of articulationlink 602 includes a hook portion 660 configured to engage thearticulation mechanism positioned within instrument 510 and the distalend includes a loop 662 dimensioned to engage a projection 664 formed onmounting portion 580 of mounting assembly 522. Projection 664 islaterally offset from pivot member 584 such that linear movement ofarticulation link 602 causes mounting assembly 522 to pivot about pivotmembers 584 to articulate tool assembly 20 (FIG. 21) in relation toproximal body portion 518.

Elongated body portion 14 (FIG. 1) or proximal body portion 518 mayinclude a retaining member for preventing articulation of tool assembly520 until a predetermined force has been applied to articulation link602. Preferably, lower housing half 594 of proximal body portion 518includes a recess 666 dimensioned to receive a biasing member 668, e.g.,a compression spring, and a ball 670. Articulation member or link 602includes a concavity 672 dimensioned to partially receive ball 670.Engagement between ball 670 and concavity 672 retains articulation link602 in the unarticulated position until it is desired to articulate thetool assembly. Referring to FIGS. 90-93, in an alternate embodiment, aspherical protrusion 674 is formed monolithically or integrally withlower housing half 594 and is dimensioned to be received within arecess, here shown as concavity 672, in articulation link 602. A cutout676 is formed in lower housing half 594 such that protrusion 674 issupported on a flexible wall 678. When the tool assembly 520 is in thenon-articulated position, protrusion 674 rests within concavity 672 toprevent movement of articulation link 602 (FIG. 91) unless apredetermined axial force is applied to link 602. When a sufficient orpredetermined axial force is applied to link 602 and link 602 is movedlinearly to articulate the tool assembly, flexible wall 678 flexesdownwardly as illustrated in FIG. 21 to permit articulation link 602 tomove-distally. It is envisioned that multiple protrusions may beprovided on the housing to permit the tool assembly to be selectivelyretained at multiple articulated and non-articulated positions.Alternately, recesses may be formed in the housing and a protrusion maybe provided on the articulation link. It is also envisioned that theabove-disclosed retaining member(s) can be formed in elongated bodyportion 14 of the device.

Referring to FIGS. 80 and 94-96, axial drive assembly 536 includes anelongated drive beam 680 including a distal working head 682 (FIG. 80)and a proximal engagement section 684. Drive beam 680 may be constructedfrom a single sheet of material or, preferably, multiple stacked sheets.Engagement section 684 includes a pair of engagement fingers 686 whichare dimensioned and configured to mountingly engage a pair ofcorresponding retention slots 688 formed in drive member 690. Drivemember 690 includes a proximal porthole 692 configured to receive thedistal end of a firing rod of an instrument 10 (FIG. 21) when theproximal end of disposable loading unit 512 is engaged with theelongated body of surgical stapling instrument 10.

The distal end of drive beam 680 is defined by a vertical support strut694 which supports knife blade 578, and an abutment surface 696 whichengages the central portion of actuation sled 234 (FIG. 22) during astapling procedure. Surface 698 is located at the base of surface 696and is configured to receive a support member (not shown) which isslidably positioned along the bottom of the staple cartridge assembly 22(FIG. 22). Knife blade 578 is positioned to translate at a positionslightly behind actuation sled 234 through a central longitudinal slotin staple cartridge assembly 22 to form an incision between rows ofstapled body tissue. Retention flange 540 projects distally fromvertical strut 694 and supports cylindrical cam rollers 700 at itsdistal end. Cam rollers 700 are dimensioned and configured to engage camsurface 209 on anvil body 204 to clamp anvil body 204 against bodytissue.

Referring to FIGS. 80 and 93-96, a locking member 702 is supported onthe proximal end of drive beam 680. Locking member 702 has a generallyH-shaped configuration including first and second legs 704 and 706, across-over portion 708, and a pair of arms 710. Each leg 704 and 706includes a lateral protrusion 712. Cross-over portion 708 is positionedwithin a slot 714 formed in drive beam 680 of drive assembly 536.Protrusions 712 are received within recesses 716 formed in lower housinghalf 594. When drive assembly is actuated by applying a predeterminedforce to movable handle 28 to advance drive beam 680 distally,protrusions 712 are forced from recesses 716 to provide an audible andtactile indication that instrument 510 has been actuated. Locking member702 also prevents inadvertent partial actuation of DLU 512, such asduring shipping, by locking drive beam 680 at a fixed position withinDLU 512 until a predetermined axial force has been applied to the drivebeam 680.

Sequence of Operation

A. Attachment of DLU

Referring to FIGS. 20 and 40-48, to use stapling device 10, a DLU 16 isfirst secured to the distal end of elongated body 14. To secure DLU 16(FIG. 41) to elongated body 14 (FIG. 40), insertion tip 193 of DLU 16 ispositioned about the distal end 276 of firing rod 58 and moved axiallyin the direction indicated by arrow “A” in FIGS. 42 and 43. A channel(not shown) formed in the distal end of elongated body 14 is providedfor slidably receiving hook portion 258 of second articulation link 256.Lugs 254 will also be positioned within channels (not shown) in thedistal end of elongated body 14. As insertion tip 193 advances intoelongated body 14, one of lugs 254 engages engagement finger 190 a oflock button 190 to move lock button 190 proximally against the bias ofspring 194 in the direction indicated by arrow “B” in FIGS. 43 and 44within elongated body 14. As lock button 190 moves proximally, abutmentsurface 190 b engages plate 192 a of plate and spring assembly 192 tourge blocking portion 192 b of plate 192 in the direction indicated byarrow “C” in FIG. 44 into notch 196 formed in firing rod 58 (FIG. 44).Positioning of blocking portion 192 b in notch 196 of firing rod 58prevents stapling device 10 from being actuated, i.e., approximated orfired, until DLU 16 has been rotated to a locked position.

Referring to FIG. 45, to lock DLU 16 in position on elongated body 14,DLU 16 and/or body 14 is rotated in relation to the other in thedirection indicated by arrow “D” in FIG. 45, to move nub 254 out ofalignment with finger 190 a of lock button 190. When this occurs, lockbutton 190 is moved distally by spring 194 in the direction indicated byarrow “E” in FIG. 48 to allow blocking portion 192 b of plate 192 a tobe moved by spring 192 c in the direction indicated by arrow “F” in FIG.48 out of notch 196 of firing rod 58. Finger 190 a is moved to aposition to the side of nub 254 to lock DLU 16 on elongated body 14. Toremove DLU 16 from elongated body after it has been locked in position,lock button 190 must be manually moved proximally and this can only bedone with firing rod 58 in the retracted position. As illustrated inFIG. 46, when DLU 16 is locked onto elongated body 14, engagementstructure 160 of articulation link 130 is operably engaged with hookportion 258 of second articulation link 256.

B. Operation of the Sensor Mechanism

Referring now to FIGS. 44 and 49-52, when DLU 16 is inserted intoelongated body 14 in the direction indicated by arrow “A” in FIG. 44,tip 193 of DLU 16 engages the distal end 170 a of sensor plate 170 tomove sensor plate 170 proximally in the direction indicated by arrow “G”in FIG. 44. Proximal end 170 b of sensor plate 170, in turn, forcessensor cap 174 to move proximally in the direction indicated by arrows.“H” in FIGS. 49 and 50. Flange 174 b of sensor cap 174 is engaged withrack lock release member 172 such that rack lock release member 172 ismoved proximally in the direction indicated by arrow “I” in FIG. 51 intoengagement with rack lock 64. Engagement between rack lock releasemember 172 and rack lock 64 causes rack lock 64 to rotate in thedirection indicated by arrow “J” in FIG. 51 to move blocking portion 64a of rack lock 64 to a position no longer obstructing engagement betweenpawl 48 and toothed rack 60 of actuation shaft 52, and to move lockingportion 64 b of rack lock 64 out of recess 52 a of actuation shaft 52.Movement of sensor cap 174 proximally also moves sensor cap tab 174 a inthe direction indicated by arrow “K” in FIG. 52 from cam member cutout176 to enable operation of the articulation mechanism of surgicalstapling device 10.

Referring to FIGS. 42A and 52A, as discussed above, stapling device 10is usable with both articulating and non-articulating DLU's. Anon-articulating DLU 16 a (FIG. 42A) does not include insertion tip 193(See FIG. 42). As such, the sensor mechanism including sensor plate 170,sensor cap 174 and lock release member 172 are moved proximally a lesserdistance when DLU 16 a is attached to elongated body 14. The distancethe sensor mechanism is moved proximally is sufficient to disengage racklock release member 172 from actuation shaft 52 but is insufficient tomove tab 174 a from cutout 176 (FIG. 52A).

Referring to FIGS. 47-49, when a DLU is secured to surgical staplingdevice 10, vertical pawl 66 is positioned beneath an abutment surface 52a formed on actuation shaft 52 and is urged to the retracted position.As illustrated in FIG. 50, in this position, cam surfaces 80 of verticalpawl 66 are positioned below cam member 76 of plunger 72. Surgicalstapling device 10 is now ready to be approximated about tissue 320(FIG. 45).

C. Approximation

Referring to FIGS. 54 and 55, to approximate the cartridge and anvilassemblies 22 and 24, movable handle 28 is moved in the directionindicated by arrow “L” in FIG. 54 through an actuation stroke, i.e.,movable handle 28 is compressed towards stationary handle 26 against thebias of torsion spring 42 to move engagement finger 62 of pawl 48 intoengagement with a shoulder 52 b formed on actuation shaft 52. Subsequentmovement of movable handle 28 through the actuation stroke effectsadvancement of actuation shaft 52 and firing rod 58. As actuation shaft52 is advanced, notch 67 formed in actuation shaft 52 moves intoalignment with vertical pawl 69 and vertical pawl 69 is urged by springmember 70 in the direction indicated by arrow M in FIG. 55 into notch 67to prevent further advancement of actuation shaft 52 (FIG. 55).

Referring to FIGS. 56 and 57, firing rod 58 is connected at its distalend to axial drive assembly 212 including drive beam 266, such thatadvancement of firing rod 58 effects advancement of drive beam 266 inthe direction indicated by arrow “N” in FIGS. 56 and 57. As drive beam266 is advanced, cam roller 286 moves into engagement with cam surface209 of anvil portion 204 (FIG. 22) to urge anvil portion 204 in thedirection indicated by arrow “O” in FIG. 57 to approximate cartridge andanvil assemblies 22 and 24 and clamp tissue 320 therebetween.

Referring to FIGS. 58 and 59, after movable handle 28 is actuated toapproximate cartridge and anvil assemblies 22 and 24, biasing member 42returns handle 28 in the direction indicated by arrow “P” in FIG. 58 toits non-compressed position spaced from stationary handle 26. Asillustrated, in this position, vertical pawl 69 is in the extendedposition with tip 69 a located within notch 67 of actuation shaft 52,thus preventing further advancement of actuation shaft 52. In theextended position, cam surfaces 80 on vertical pawl 69 are aligned withcam member 76 of plunger 72 (See FIG. 59).

D. Operation of the Plunger

Referring to FIGS. 60-62, when stapling device 10 is approximated,vertical pawl 69 is engaged within notch 67 of actuation shaft 52 tolock actuation shaft 52 in the approximated position. To release orunlock the actuation shaft 52 and put stapling device 10 in a fire-readyposition, plunger 72 is provided. When plunger 72 is pressed in thedirection indicated by arrow “Q” in FIG. 61, cam member 76 of plunger 72engages cam surfaces 80 of vertical pawl 69 to urge vertical pawl 69 inthe direction indicated by arrow “R” in FIG. 61 to its retractedposition. In the retracted position, tip 69 a of vertical pawl 69 isoutside of notch 67 of actuation shaft 52 and device 10 is in afire-ready position. Vertical pawl 69 is maintained in the retractedposition by engagement between cam member 76 of plunger 72 and recesses82 on cam surfaces 80 of vertical pawl 69.

E. Firing the Surgical Stapling Device

Referring to FIGS. 63-65, to fire stapling device 10, movable handle 28is moved in the direction indicated by arrow “L” in FIG. 63 through asecond actuation stroke during which, engagement finger 62 of pawl 48engages toothed rack 60 of actuation shaft 52 to advance actuation shaft52 and firing rod 58 distally. Referring again to FIG. 60, as actuationshaft 52 moves distally, a second abutment surface 52 b formed onactuation shaft engages vertical pawl 69 to move vertical pawl 69downwardly in the direction indicated by arrow “R” in FIG. 64 todisengage cam member 76 of plunger 72 from cam surface 80 of verticalpawl 69 and allow spring 78 to return plunger 72, in the directionindicated by arrow “S” in FIG. 64, to the neutral position.

Referring to FIGS. 66 and 67, as firing rod 58 is advanced in the mannerdiscussed above, drive beam 266 is advanced in the direction indicatedby arrow “T” in FIGS. 66 and 67 to advance actuation sled 234 throughstaple cartridge 22 to simultaneously sever tissue with knife 280 (FIG.31) and drive pushers 228 to sequentially eject staples 226 from thecartridge.

Surgical stapling device 10 is adapted to receive DLU's having staplecartridges with staples in linear rows having a length of from about 30mm to about 60 mm. Each actuation stroke of movable handle 28 duringfiring of surgical stapling device 10 advances actuation shaft 52approximately 15 mm, although other lengths are envisioned. Accordingly;to fire a cartridge having a 45 mm row of staples, movable handle 28must be moved through three actuation strokes after the approximating orclamping stroke of movable handle 28.

F. The Retraction Mechanism

FIG. 68 illustrates operation of the retraction mechanism of surgicalstapling device 10. In use, when return knobs 36 are pulled rearwardlyby a surgeon in the direction indicated by arrow “U” in FIG. 68,coupling rod 82 initially moves release plate 86 rearwardly in relationto actuation shaft 52 as rod 82 slides in slots 84 of actuation shaft 52such that pins 88 cam release plate 86 downwardly in the directionindicated by arrow “V” to a position covering toothed rack 60 ofactuation shaft 52 and disengaging finger 62 of pawl 48 from toothedrack 60. When coupling rod 82 is pulled rearwardly to a position atwhich it engages the back end 84 a (FIG. 5A) of slots 84 additionalrearward movement knobs 36 will effect proximal movement of actuationshaft 52 and firing rod 58.

G. Operation of the Articulation Mechanism

Referring to FIGS. 69-72, articulation lever 122 is pivotable to effectarticulation of tool assembly 20. More specifically, when articulationlever 122 is rotated or pivoted about lever pin 132 (FIG. 12),projection 134 (FIG. 11) of lever 122 causes cam cover 126 and cammember 124 to move across transverse channel 120 of rotatable knob 32.Movement of cam member 124 across transverse channel 124 causes steppedcam slot 146 to move in relation to first projection 150 of cam pin 148,thus causing cam pin 148 to move through longitudinal slot 144 inrotatable knob 32 (FIG. 11). Longitudinal movement of cam pin 148effects corresponding longitudinal movement of drive member 128 andarticulation link 130. As illustrated in FIG. 69 when lever 122 isrotated in a counter-clockwise direction, articulation link 130 is movedproximally or retracted. As illustrated in FIG. 70, when lever 122 isrotated in a clockwise direction, articulation link 130 is moveddistally or advanced.

As illustrated in FIGS. 71-73, the distal end of articulation link 130is operably connected to the proximal end of second articulation link256. The distal end of articulation link 256 is connected to projection262 on mounting assembly 200 (FIG. 73). Projection 262 is laterallyoffset from pivot members 244 such that movement of articulation link256 causes articulation of tool assembly 20. More specifically, whenarticulation link 130 is retracted (FIG. 69), articulation link 256 isretracted and tool assembly 20 is articulated in a direction indicatedby arrow “X” in FIG. 75. When articulation link 130 is advanced (FIG.70), articulation link 256 is also advanced and tool assembly 20 isarticulated in a direction indicated by the arrow “Y” in FIG. 74.

Referring to FIGS. 76 and 77, rotation knob 32 is rotatable in relationto handle assembly 12 to rotate elongated body 14 and DLU 16, includingtool assembly 20, about a central longitudinal axis of elongated body14. As illustrated in FIGS. 76 and 77, surgical stapling device 10 canbe rotated while tool assembly 20 is articulated. Device 10 can also berotated and then articulated.

H. Operation of Lockout Mechanism

Referring now to FIGS. 36-38, 78 and 79, the sequence of lockoutoperation will be described in detail. In FIG. 38, lockout device 288 isshown in its prefired position with horizontal cams 300 and 302 restingon top of projections 330 (FIG. 36) formed in the sidewalls of lowerhousing half 252 (FIG. 37). In this position, locking device 288 is heldup out of alignment with projection 332 (FIG. 37) formed in the bottomsurface of lower housing half 252, and web 298 is in longitudinaljuxtaposition with shelf 334 (FIG. 38) defined in drive beam 266. Thisconfiguration permits the anvil 24 (FIG. 39) to be opened andrepositioned onto the tissue to be stapled until the surgeon issatisfied with the position without activating locking device 288 todisable the disposable loading unit 16.

As shown in FIG. 72, upon distal movement of drive beam 266, lockingdevice 288 rides off of projections 330 (not shown) and is biased intoengagement with base lower housing half 252 by spring 304, distal toprojection 332. Locking device 288 remains in this configurationthroughout firing of the apparatus.

Upon retraction of the drive beam 266 in the direction indicated byarrow “U” in FIG. 78, locking device 288 passes over projections 330 andrides over projection 332 until the distalmost portion of locking device288 is proximal to projection 332. Spring 304 biases locking device 288into juxtaposed alignment with projection 332, effectively disabling thedisposable loading unit. If an attempt is made to reactuate theapparatus, the firing rod 58 will abut a proximal end surface of lockingdevice 288 which surface is diagonally sloped to impart a moment aboutpivot pin 342 such that the distal end of locking device 288 isrotationally urged into contact with projection 332. Continued distalforce in the direction indicated by arrow “AA” in FIG. 79, will onlyserve to increase the moment applied to the locking device thus thelocking device will abut projection 332 and inhibit distal movement ofthe firing rod 58.

It will be understood that various modifications may be made to theembodiments disclosed herein. Therefore, the above description shouldnot be construed as limiting, but merely as exemplifications ofpreferred embodiments. Those skilled in the art will envision othermodifications within the scope and spirit of the claims appended hereto.

1-24. (canceled)
 25. A surgical stapling device comprising: an elongatedbody portion defining a longitudinal axis; a tool assembly pivotallysupported at the distal end of the elongated body, the tool assemblyincluding an anvil assembly and a cartridge assembly housing a pluralityof staples, the anvil assembly and cartridge assembly being movablymounted in relation to one another between open and closed positions; aflexible drive assembly having a distal end configured to translatethrough the cartridge assembly to eject the staples therefrom, theflexible drive assembly being bendable relative to the longitudinal axiswhen the tool assembly pivots; and a first support member positionedadjacent the pivot axis on a side of the flexible drive assembly, thefirst support member having a first end fixedly attached to the toolassembly and a second end fixedly attached to the elongated bodyportion, the first support member having a central portion defining anopening allowing the first support member to lengthen when the toolassembly pivots.
 26. A surgical stapling device according to claim 25,wherein the cartridge assembly includes a plurality of pusherscorresponding to the plurality of staples, and a sled having cam wedgesfor interacting with the pushers to drive the plurality of staplestoward the anvil assembly, at least some of the cam wedges being offsetwith respect to at least some other cam wedges.
 27. A surgical staplingdevice according to claim 25, wherein the tool assembly is pivotableabout a pivot axis.
 28. A surgical stapling device according to claim25, further comprising a second support member on an opposite side ofthe flexible drive assembly, the second support member lengthening whenthe tool assembly pivots in a second direction.
 29. A surgical staplingdevice according to claim 25, wherein the first support member includesa U-shaped portion that flexes when the tool assembly pivots.
 30. Asurgical stapling device according to claim 29, further comprising alimit member positioned about the U-shaped portion to limit the extentto which the U-shaped portion can flex.
 31. A surgical stapling deviceaccording to claim 29, wherein the U-shaped portion extends outwardlywith respect to the flexible drive assembly.
 32. A surgical staplingdevice according to claim 25, wherein the first support member has atleast one end that has a J-shaped member.
 33. A surgical stapling devicecomprising: an elongated body portion defining a longitudinal axis, andhaving proximal and distal ends, the elongated body including a housingdefining a recess; a tool assembly pivotally supported at the distal endof the elongated body portion, the tool assembly including a cartridgeassembly housing a plurality of staples and an anvil assembly, the anvilassembly and the cartridge assembly having open and closed positions; aflexible drive assembly having a distal end configured to translatethrough the cartridge assembly to eject the staples therefrom, theflexible drive assembly being bendable relative to the longitudinal axiswhen the tool assembly pivots; a first support member positionedadjacent the pivot axis on a side of the flexible drive assembly, thefirst support member having a first end disposed in the recess in thehousing and fixedly attached to the housing, wherein the first end ofthe first support member includes a retaining portion having anattachment member with tips that are angled to engage and lock into arecess in the tool assembly; and a locking member press fit in therecess in the housing.
 34. A surgical stapling device according to claim33, wherein the tool assembly is pivotable about a pivot axis which issubstantially perpendicular to the longitudinal axis of the elongatedbody.
 35. A surgical stapling device according to claim 33, wherein thefirst support member has a central portion defining an opening allowingthe first support member to lengthen when the tool assembly pivots. 36.A surgical stapling device according to claim 33, further comprising asecond support member on an opposite side of the flexible driveassembly, the second support member lengthening when the tool assemblypivots in a second direction.
 37. A surgical stapling device accordingto claim 33, wherein the first support member includes a U-shapedportion that flexes when the tool assembly pivots.
 38. A surgicalstapling device according to claim 37, further comprising a limit memberpositioned about the U-shaped portion to limit the extent to which theU-shaped portion can flex.
 39. A surgical stapling device according toclaim 37, wherein the U-shaped portion extends outwardly with respect tothe flexible drive assembly.
 40. A surgical stapling device according toclaim 33, wherein the first support member has at least one end that hasa J-shaped member.